Introduction of DDT (dichloro-diphenyl-trichloroethane) and the following move towards indiscriminate use of synthetic chemical insecticides led to the contamination of water and food sources, poisoning of non-target beneficial insects and development of insect pests resistant to the chemical insecticides. Increased public concerns about the adverse environmental effects of indiscriminate use of chemical insecticides prompted a search for alternative methods for insect pest control.
One of the promising alternatives has been the use of biological control agents. There is well-documented history of safe application of Bt (B. thuringiensis, a gram positive soil bacterium) as effective biopesticides and a number of reports of expression of delta-endotoxin gene(s) in crop plants are available. Only a few insecticidal sprays are required on Bt transgenic crops, which not only save cost and time, but also reduce health risks. In some cases, insects can develop resistance to different insecticidal compounds, which raises the need to identify alternative biological control agents for pest control.